Apparatus for the electrical transmission of visual images



April 17, 1928." 1,666,594

P. L. CLARK APPARATUS FOR THE ELECTRICAL TRANSMISSION OF VISUAL IMAGES i e March 26, 1923 2 sheets-sheet 1 INVENTOR.

7PM 12 M April 17, 1928. 1,666,594

P. L. CLARK APPARATUS FOR THE ELECTRICAL TRANSMISSION OF VISUAL IMAGES Filed March 26, 1925 2 Sheets-Sheet 2 lzo I2 IZOJ Fla]? .281]

wwmzss INVENTOR 7AA, W I PM 2.

Patented Apr. 17, 1928.

' UNITED. STATES.

PA UL L. CLARK, OF BROOKLYN, NEW YORK.

APPARATUS FOR THE ELECTRICAL TRANSMISSION or m muons.

. Application filed Jamil 2s, ieaafsemi No. s27,s

My invention relates to improvements; in machines for the transmlsslon and receiving of electrical or magnetic impulses, either by wire or radio, of point by point, line by line, or spot by spot, scenes at one location so that an image of the scenesmay be produced upon a screen or photographic, plate for observation at a distant point or station; or for the transmission or reception, or both, or periodic or non periodic waves produced by means of light waves or electrically, magnetically or otherwise; and the object of, my-invention is to provide a simple optical and mechanical arrangement for both or either the receiving and sending apparatus.

ll attain these objects by the mechanism illustrated in the accompanying drawings in which Y Figure 1 is a horizontal sectional part plan of the transn'iitting apparatus; Fig. 2 is a horizontal sectional part plan of the receiving apparatus; Fig. 3 is a horizontal sectional part plan of a system similar to that shown in Fig. 1; Fig. A: is a broken elevation showing a modified mechanism similar to that in Fig. 3; Fig. 5 is a diagrammatic section through the axes of the several component parts shown, showing path'sof rays to and from a 'screenprovided with curved specular elements (similar to that described in applicants Patents 1,122,192,

1.279.262, 1,535,985 and his copending ap plication-Ser. No. 18,241); Fig. 6 is a sectional view of a circular disk provided with adjustable reflectors like those shown in Figs; 1, 2 and 3; Fig. 8 is a section of Fig. 6 on A-A; F ig. 7 is any end elevation of a part of a. circular diskfhaving oblique reflecting elements, this disk .being a modification of the disk shown in Figs. 6 and 8; Fig. 9 is a frontelevation of an adjustable aperture plate for use with the mechanisms shown in Figs. 3 and 4; Fig. 10 is a-part plan of a modified arrangement like that in Fig.- 2; Fig. 11"is a cross-section of a curved reflecting screen claimed in my copending' application S.'N. 15,350 which may be used with the apparatus shown in Figs. 1, 2, 3, etc; Fig. 12 is a front elevation of a part of a prismatic ring similar to that shown in applicants Patent No; 842,860. this ring. to be used to take the placeof the reflecting rings or disks shown in Figs. 6, 7, 8, and for tracing-parallel or substantially parallel, or slightly eccentric rings or hands of light ter for use in instruments using four disks;

Fig.16 is a diagrammatic elevation showing V the sequence of the reflecting elements on adjacent, disks; Fig. 17 is aplan'view of a modified system using a shutter and having a bank of light-sensitive cells; and Fig. 18 is a front elevation of Fig. 17.

Similar numerals refer to similar parts throughout the several views.

In. F lg. 1, an illuminated spot 31 (being one ofniany small spots of different shade or color or tone comprising the picture to be transmitted) reflects certain rays of light which enter a lens a and are focused upon a spot p on a reflecting screen 8 which may be either matt or specular as desired. Certain .rays from p are reflected in the direction indicated by the arrowed line 9 and fall upon the revolving disk 18 which is pro vided with oblique reflecting elements 17 which reflect the rays 9 as shown at.10 (the width of this reflected-pencil of rays being shown at 11) ,to pass through the aperture conductivity or whose effect-upon or coopcratlon with any electr cal circuit or current is affected'to vary or produce electrical impulses of an intensity substantially proportional (or varying in predetermined ex tent) to the intensity through equal periods of exposure to pencils of light of substantially equal size or cross-section falling upon the said cell.- Andtothis end it is desirable,

when moving pictures are tobe transmitted,

that the cell 13 reach its saturation point in the-minimum period required for its exposure to one spot of the view to be transmitted, and also'tha-t the effect of the bright est spot impulse received upon the cell be deadened or neutralized (so that at the end i 5,

of any given impulse produced the effect will'not continue over into 'the period tobe giventothe next exposure) in order to confine the effects within the duration and limits of the-brightest and darkest spots, such that for instance, twq bright spots in succession will not produce one semi-bright and one over-bright spotf-which is theioharacteristially zero inertia in the cell 13, wires 14'," 15 lead off throughsuibstrips 1, 2,

tie of selenium cells; i.'e., the sensitivity of the cell should be such that there is substansystem. From the able electrical connections 'andauxiliaries (not shown) to either a wire or wireless (broadcasting) electrical transmission system which deliver .the impulses produced in the circuit 14, 13, 15 to the'circuit-16, 21, 16 Fig. 2. The disk 18. is driven by a motor 19, the

whole revolving about the axis 20, the operation of the system being that as the disk 18 revolves rapidly, each element 17 refleets over successive vertical or horizontal of light from the view, the paths of the rays being shown by the arrowed lines. Itis also possibleto-use the transmitting mechanism direct ,without the interposition of the lens a and screen 8 by considering the view itself as occupying aspace in the angle subtended by the'screen, in which case it will be advantageous ito provide elements on the disk 18 which'are either plane or concaved to a degree to. effect-a slight concentration and'focusingof the rays upon the aperture plate 12,-'to the end that too great scatter;

ing of rays and confusion of points due to tion depends upon.-

overlapping be'avoided, in order to secure sharpness of definition. A converging. or diverging lens .(not shown) may be placed either in front or rear of the aperture plate 12 to secure proper dispositiono f the rays over the cell 13, when desired. 7

In Fig. 2, rays from a light source L are received by the lens I) and concentrated upon a reflecting diaphragm 22 whose configurathe' strength, .or frequency of the impulses received in the circuit 16, 21, 16', so that a strong impulse renders the d1aphragm-22 of such concavity that itacts tofocussubstantially all the rays received upon lair or-identical, on so that the period of it to pass through the aperture plate 25; and fell upon the 'revolving, disk-26 driven by the motor27 operating in synchronism with the motor 20, Fig.

the disks 18 and 26 being preferably simipassage of the beamof'light through the angle. subtended by the screen be substan-v tially the samedboth in rec iv r an r ilsmitter, to the end that corresponding spots 'registerat correspondingly relative loca- 'tions on both instruments, or. follqw each other at determinable intervals duel to the inertia'of the system. Although an electromagnetic. circult transmitting impulses to a reflecting diaphagm is here shown, it should be understood to lie withinthe scope of the invention to employ any other known means ofv varying the brilliancy of a pencil or beam or of alight source itself by means of variations ofinten'sity in, or. frequency of, electrical impulses applied to a device whose light emanating, producing, radiat- 3, etc., of the screen s fa striping, transparency, reflecting or transmission properties are affected by varlatlons of elec- "trical character.

da1nping the impulses produced by or employed wit may be used" Also, any known means of 1ncreas1ng,' dlmlnishing, amplifying or hthe apparatus herein 7 described In Fig. 3, rays pass through the lens a,

as shown by the arrowed lines, t9 fall upon the screen 8", those falling upon one-half 29 of the screen being received upon the disk 41, while those falling upon 30 fall upon the disk 42, through aperture plate 38 and the revolving shutter 39 (later described), the number of disks, slotsi which the screen is divided being equal, it

' being understood that the number of parts here shoWn-.two1s merely in order to signify that there may be more than a single 85 screen and a single'disk used when desirable, each screen (or proportional part of.

any one screen) being used in combination with an ndependent shutter, or a sector of a ,common shutter. Or, instead of using a plurality of disks .all revolvingat equal speed, there may be used asingle disk revolv'ing at a proportionately reduced speed, i of increased diameterfand provided with an inversely greater number of reflecting elements, the idea being merely to insure equal periods of passage of the pencil of'ray-s cooperating with any given jelement over the screen area which the said element controls. The disks 41, 42, the gear 46 and motor 47 are all vattached to the'spindle 44 passing through the bearing 43, the

46 meshing with the gear 45 which is twice thev diametral pitch of. the gear 46/ The gear 45 and revolving shutter 39 are secured the other half 'after passing gear.

n'the shutterand portions'into to the splndle 48 which runsin the bearing 40, so that theangnlar velocity ratios of the systems on the spindles 44 and 48 are inversely as the number of disks 41',- 42; or,

more correctly, as the number of sets of ele gear 64-which is fastened to and drives a handle 67 and meshing which runs in abearing 62 shaft 56 passing through a bearing 57 and to. c

which is secured the stator .47 of a motor. This motor is either electric or of other type and should be run synchronously or close tof synchronous speed-both in the receiving.

7 or properly geared to the light reflecting elements, as 26,. Fig. 2,"to cause similarspots to register si-- and transmitting apparatus,

multaneously inboth instruments. To the 1 spindle 56 are'also secured collecting rings insulation 56 and connected with the stator of the motor or, if desired, to the rotor, de pendmgupon what type. of motor is used; Power for running the motor is supplied through leads 59, 60 connected to statlonary brushes 86, so that the angular position of the stator may be varied at will by turning the gear 65. To. the rotor 52 isattached a spindle 44 which runs in av bearing 43and to which are secured disks 41, 42 and a gear 46 meshing with a gear which is secured to the same spindle as a revolving shutter 39 which runs in the bearing 40. The shutter 39 is provided with two concentric apertures 50,51, each subtending an arc of a" complete circle inversely proportional to the number of disks used, and eachof suitable width and the 'two suitably spaced so that only one disk is exposed at a time to the effect of light rays from the screen (see Fig. 3), each .disk

beingv exposed through, substantially .a full revolution and the two disks being exposed consecutively An adjustable aperture plate (see Fig.9) 38 having a horizontal aperture of "length suflicient to permit rays to enter and leave bothslots 50, .51, is suitably positioned in front of the shutter 39. When more than two disks are usedsay, five .the ratio of gearing between shaft and shut-- ter should be as one to five, the shutter should have five concentric apertures each subtending adjacent apertures of 72 degrees, and each aperture should lineup with a sep- 8 arate disk, and the screen should be made up of five sections each section provided with elements controlling the direction of the reflected rays so thatthey fall upon and .co-

operate with the disk or disks utilized for receiving or transmitting the points of the view received upon that particular part of the screen as a whole.

In Fig. 5, the center of curvature of the convex reflecting specular elements 82 on the screen 81 is behind the screen (one shown at the point 7 0'), the angle subtended by the area'of the element presented to the beam of light 83, and the angle of the general. sur face of (the element as a whole being such that the rays reflected as shown by the ar-" rowed lines 7 6, 77 will bereceived upon and reflected by the element upon which they fall'in the general direction shown by-theline 79 which forms the same angle with the normal 78 to the element at the point ofintersection of the axis as does the said axis. 75. If the lines 76, 77 are produced to pass .it-hroughthe screen they intersect at a point 72 in the plane 71, back of'the plane ofthev screen. so that the angle 74 formed between them is substantially twice the angle 73 formed between the normals to the' outside edges of the element;- in other; words,'-tw1c e the angle of curvature of the element. This type of multi-power reflecting-screen, 'to-.

getherwith analysis of its design tosuit various COIldllJlOIlS of light projection and.

reflection to embrace viewing angles of predetermined magnitude is described in appli;

cants patents aforesaid. A flat screen or a plurality of screens such as 81 provided.

with convex spherical elements of the proper curvature and angle and at the proper angle to the incident pencils or cones of light from a lens as c, Fig. 3, and conforming with the design indicated in Fig. 5 will be adaptedfor use in the several instances here shown on account of securing a concentrated direc tional beam or limited divergence. {Since the area of the elements presented to the light affects the sharpness of. definition, their side should be determined by the degree of desirable delineation, whichin turn is govimpulses maydoe transmitted, it being understood tlfat the higher the rate of 'transmis erned by the rapidity with whichsuccessive sion obtainable the greater thesharpness and Y size of the picture, so that when moving pictu'res are to be transmitted the speed ofsuccessive impulses should be from 100,000 per second, upward, for a single circuit system. In Figs. 6 and 8, plane or slightly concave similar or identical reflectors 98 are spaced to subtend equal angles around the spindle 44 and are adjustable by means of screws,

97 threaded into flanges 96, 99 of the member 95, the whole arrangement taking the place of one or more disks 41', 42, Figs. 3 and a .the reflectors maybe cementedin place and the. screws removed.- It should be understood that the angle 'subtended by each reflector with respect to the' axis about which the groupiof reflectors revolves is substan tially half the angle subtended bythevertical height of the screen as in Fig. 1, with respect to the said axis, so that each successive reflector 'is presented to successive strips of the screen in rapid succession. and

with a minimum timeloss between them.

IIt'will be seen that each reflector'98 is perpendicular to a plane passing. through the axis 44, but all are of varying and constant-.

ly increasing degreesof obliquity with respect to a plane at right angles to the said axis-,the angle ofvari'ation ofobliquity being substantially-half the angle subtended by the strips, as 1, 2, etc., Fig. 1. with respect td the middle point on the reflector, as 17 Fig.1. The dimensions of the active (work- 7 ing part,.as determined by the shutter and aperture plates, Figs. 3 and 4) may be readily determined. by experiment with sources of different-dimensions and divergence, or

ofthe general surface of successive reflectors" I the disks, a p'er disk.

by the use of additional lenses or aperture plates" to secure a parallelling of' the rays' or the elimination of undesirable stray rays.-

Also, the sizes, design, spacing, dimensions, speed, proportions and arrangement of the various factors or parts going tomake up the complete outfit shown in this specification may be determined by experimentor in ac-. cordance with optical, mathematical, .mechanical, electrical,- physical or other. scientific or basic principles governing -the design,

\ use, operation and maintenance of apparatus of thecharacter herein described.

In Fig. 7 the general surface ofthe disk. 49 is cylindrical, or more like aspiral, since.

themean point of each differently oblique reflecting face 85 lies on a circle. The gen eral surface of each element 85 is equally oblique to adjacent elements in a plane taken through the middle of the disk 49 at right angles to the spindle 84, and the anglebetween the elements and the said plane varies i i-accordance with the description given for Figs. 6 and-8. A slight modification of this type of disk is shown in my copend'iiig application, S N.'162,311. This type'of disk is to -be used'in place of other types of disks, if

desired, the advantage of tipping the elements like ratchet teeth is to enable the placing of-the cell 13, Fig. 1, or the receiving device, Fig. 2, below or above the horizontal plane through the middle of the screen. Instead of arranging the elements like saw teeth, itisevident that they may be grouped or assembled with contacting edges, or substantially so, as shown in Fig. 6, but ground and polished and integral with thedisk itself. 'This disk should'be made of, or plated with, silver or some highly reflecting, metal,

andall elements should subtend substantially equal arcs or'angles of the circumference of the disk, although'this is not necessary, since theprime requireme t' is that when I both the transmitter and receiver employ reflecting disks of the type here'shown, the j angular velocity of the elements or their. periods of operation at both the receiving and sending stations be identical. Any desired number of disks may. be used either side by side or'on different shafts, 'an d any.

' desirednumber; of elements may 'be cut on good number being forty to fifty In Fig. 9, the thinmetal plate 38 has an aperture 103 whose opening may be varied yby sliding the shutters 102 under the screw reflectors 113 is one of the types shown in applicants patents aforesaid, and is adapted for use in .the device in combination with objective lenses having a curved focal 'surface instead of a true focal plane.

In. Figs..12 and 13, faces 107. are ground and polished on the periphery of the glass ring .106. Light rays 109 enter the flat-surface 108,- pass to the reflecting surface 111, are reflected to the outside of the ring and refracted at different predetermined angles by the faces 10? as the ring is revolved upon its axis- In Fig. 14, the disk 18 receives and re- I fiects rays as shown by the arrowed lines to fall upon a disk 18* which revolves in synchronisin with the disk 18 and on an axis at. right angles thereto. As these disks re-. volvethe light pencil moves'i'apidly over the bank of sensitive cells 114 each of which is momentarily connected in the transmit ting circuit by means of a contacting device operating in synchronism with the passage of the light beam over the cells, the'wires 115 leading to the contactor (not shown).

In Fig. 15, the metal shutter 35) is for use with-a system having four disks, each apei tiire 116, 117,.etc., subtending an angle of ninetydegi ees, and arranged so that as the" shutter revolves. successive disks are-exposed so as to operate in cycles.

In Fig. 16, the disks are I volve clockwise and to be rigidly mounted .side by side on the same spindle, as in Fig.

3 (and not edge to edge, as :here shown, for diagrammatic purposes). j The angles of the assumed to rc- I several reflectii'ig faces are such that 87,91

and v are theelements controlling the direction of light to the'vertic'al strips each the farthest to-the ri lit-of each section of a threepart screen, t e' other elements on each disk being as described for Figs. 3, 6, etc. I i a In Figs.' 17 and 18, a lens 122 in the trans mitter receives light front the View (not shown). and directs these raysto a/ screen having three partsd, e, f, one-third of thetotal screengarea being exposed at any given instant byl; means of the continuous belt shutter 128' running on rollers 132 supported by bearings 133' a'ndhaving three equally spaced apertures. Consider a single section,

d-z-this section is three elements wide -by gle cell, as 120 in a bank of light-sensitive cells each of which is electrically connected nine high-(see Fig. 18) and each element, v as reflects light to a corresponding sinas shown in Figs. 1, 14,'or, otherwise, as is well known in the art.

Iclaim z. 1. In app'aratusof the class described, in-

combination, aplurality' of c'oaxially dis- 'pose'd disks."i'otatable about a given axis,

means for rotating said disks, each .of said disks being provided with. a plurality ofmirrors, the said mirrors on one-diskconrived from a'suitable source to illuminate successively parts comprising a iven area, and the mirrors on adjacent dis s controlling the light to illuminate areas adjacent the aforesaid areas, and means for successively and cyclically exposing each of said disks during a predetermined portion of a complete revolution of each of said disks to the aforesaid beam of light.

2. In apparatus of the class described, means rotatable on a fixed axis, said means including a plurality of substantially juxtaposed light-deflecting elements disposed to embrace an arc of more than 360 degrees 'relative to the aforesaid axis.

3. In apparatus of the class described, means rotatable on a fixed axis, said means including a plurality of light-deflecting elements, the sum of the angles subtended between the centerlines of all of said elements,

in succession, being morethan 360 degrees relative to the aforesaid axis.

4. In apparatus of the class. described, a plurality of light-deflecting elements disposed upon a surface of revolution andmeans for successively illuminating each of said elements by light rays derived from a suitable source, the length of arc embraced by all of said elements, in succession, being more than 360 degrees.

5. In apparatus of the class described, in combination, a plurality of-light-deflectors disposed in a group rotatable on a fixed axis, said group as a whole comprising more than 360 degrees, means for rotating said group on said axis, a source of li ht, and means for directing rays from sai -source successively upon each of the said light-deflectors.

6. In apparatus of the class described, in combination, a. plurality of light-deflecting elements disposed on a rotatable member and each controlling the direction of light rays to one of a plurality of different areas on a given surface, the sum of the angles between the centerlines of all the said ele-. ments, in succession and relative to the axis of rotation of the aforesaid member, being more than 360 degrees, and means for exposingsaid elements each successively to control rays from said rotatable member to the given surface aforesaid.

7. In apparatus of the class described,' in combination, a rotatable group comprising a plurality of light-deflecting elements dispoied at substantially equal angles relative to the axis of saidgroup and collectively embracing morethan 360 degrees of arc relative to said axis, and means for successively and cyclically exposing each of said elements to light rays from a suitable source, and means for substantially simultaneously rendering the remainder of said element-s optically inoperative.

8. In apparatus of the class described, in combination, a pluralityv of light-deflectors disposed in a group mounted on a shaft rotatable about aflfixed axis, said group as a Whole comprising more than 360 degrees, an electric motor mechanically connected to said shaft, a source of-light, means for successively exposing each of said light-deflectors to rays from said source, said motor comprising a stator and a rotor, said rotor being mounted on' said shaft, suitable bearings on said stator, said shaft being rotatable in said bearings, suitable bearings for supporting said stator coaxial with said rotor, means including sultable gearing for rotating said stator coa'xially with said rotor, suitable electrical connections to said stator and to said rotor, said means for exposing said light-deflectors being controlled the rotation of said rotor.

In testimony whereof, I, PAUL L. CLARK, have si ned my name to this specification this 19t day of March, 1923.

. I PAUL L.'CLARK. 

